In North America and in most civilized and developing countries of the world, rail transportation of both freight cars and passenger cars, is an important part of each country's economic infrastructure. This is especially true in heavily urban areas in North America and Europe, and also in large geographical areas such as the United States and Canada. Most cities in developed countries of the world contain hundreds, if not thousands, of miles of railway track. Indeed, a large and developed country, such as the United States, might contain several hundred thousand miles of railway track, including main lines, marshalling yards, commuter lines, and so on.
Most types of railway tracks are supported on a plurality of individual ties spaced one from another along the length of the railway track. The ties are typically about two and one-half meters long and about fifteen to twenty centimeters in width and length. The rails are secured to the ties in any one of a variety of ways, such as by means of large spikes, or by means of specially designed clips engaging co-operating clip receiving members embedded in the ties. The ties keep the rails spaced apart at a predetermined distance. The ties are further designed to carry the static and dynamic loads of freight and passenger trains travelling at various speeds, including relatively high speeds, perhaps well in excess of one hundred miles per hour. Such ties include wood ties pressure impregnated with a preservative such as creosote, concrete ties and steel ties.
The most common type of railway tie is a conventional wood tie. Wood railway ties are the preferred railway ties in North America, for instance, since they can stand climatic change, and are relatively low cost to purchase and initially install, again compared to other types of railway ties.
Such conventional wood railway ties a have several disadvantages associated with them. Firstly, they are obtained by cutting down trees, which is generally considered environmentally undesirable. Considering the number of miles of railway lines there are in North America, for instance, a staggering number of wood railway ties must be used each year. Indeed, recent statistics indicate that twelve million wood railway ties were installed in North America in 1993, which number appears typical of the past few years. These twelve million wood ties were taken from hardwood trees such as oak and hard maple. An average of only three eight-foot long ties are available from a mature hardwood tree. Accordingly, over a five year period, for instance, about 20 million hardwood trees would need to be cut down to serve the railroad industry in North America alone. If this number is translated to use throughout the world, the number of trees that must be cut down over a five year period could be in the order of 100 million, which is a unacceptably high number and certainly has a severe impact on the environment. In these days of environmental consciousness, it is highly undesirable to continue to use wood ties.
Further, wood ties need to be replaced every few years, and thus tend to be somewhat expensive over a long period of time. The typical service life of a wood railway tie on a North American railway line is about ten years before the railway tie must be removed and replaced with a new tie. Considering the number of railway ties replaced in North America each year, and considering all developed countries in the world where railway ties are used, and therefore replaced, the number of railway ties replaced per year is absolutely staggering, thus leading to higher long term costs.
In use, wood railway ties are supported and somewhat surrounded by a compacted granular bed known as ballast. The ties tend to shift in the ballast bed, due to the extreme dynamic loading on the railroad track by a passing train. Wood railway ties therefore require routine maintenance in order to ensure that they are properly supporting the railway track rails. Also, the ballast bed requires consistent and regular maintenance in order to keep the individual pieces of ballast in place.
Also, the preservatives that are used to treat wood railway ties in order to protect the wood railway ties from insects, rotting, and so on, are typically made from hazardous chemicals, such as creosote, which is a known carcinogen. It is therefore undesirable to manufacture such railway ties, to have such railway ties in the environment during use, and also generally unacceptable to dispose of old used railway ties because of the impact on the environment.
Concrete railway ties are popular in Europe, and in other places in the world, where the availability of hardwood is limited. Concrete railway ties do have problems associated with them, however. Firstly, they are relatively expensive and can crack or spall over a number of years when used in areas of dramatic climatic change. Most significantly, they can suffer from rail to tie erosion under the heavier rolling stock loads in North America as compared to the lighter and smaller locomotives and passenger and freight cars used in Europe.
Steel railway ties realize limited use in North America and other parts of the world. Susceptibility to rust and a high noise level during use, which is unacceptable on passenger trains, limits their acceptability.
It is an object of the present invention to provide a railway tie that can be produced and used with little or no negative enviromnental impact.
It is another object of the present invention to provide an improved railway tie that lasts significantly longer than conventional wood railway ties.
It is yet another object of the present invention to provide an improved railway tie that costs less in terms of continuing maintenance.
It is still another object of the present invention to provide an improved railway tie that will not crack in cold weather.
It is a further object of the present invention to provide an improved railway tie that is suitable for use in virtually all types of railway lines.
It is yet a further object of the present invention to provide an improved railway tie that absorbs the noise of a train passing thereover.